BATHYMETRIC MAPPING OF CORAL REEFS IN THE RED SEA (HURGHADA – EGYPT) USINGLANDSAT7 ETM+ DATA

摘要

For monitoring threats posed on coral reefs a bathymetric map is useful as a base to locatevulnerable areas. For mapping shallow features as coral reefs in the Red Sea, conventionalecho sounding methods are usually inappropriate due to the draught of the vessels used. Hereremote sensing can bring a solution. Different methods have already been developed to mapbathymetry using passive remote sensing. In this paper the modified Depth of Penetrationmapping method suggested by Green et al. (2000) is implemented on a Landsat7 ETM+ image.This method is mainly based on the different attenuation coefficients of sequencingwavelengths in water. Using additional ground-truth observations, depths can be estimated.Although this method results in an acceptable bathymetric map, some deviations from groundtruthoccur. These differences caused by errors inherent to the method used, field sampling orimplementation, are examined and possible solutions are presented.